Perrygraf Metalcutting Slide Rule for Dreis & Krump

The Chicago firm of Dreis & Krump distributed this yellow paper slide rule as an aid to those using the machine tools it manufactured to cut, bend, and punch sheet steel and brass. The rule has a paper slide and is held together with metal rivets. The front of the instrument and slide combine to produce a table for determining the length of sheet steel required, assuming the piece has various numbers and shapes of bends. The reverse has a rule for calculating tons pressure per lineal foot, given the gauge of the metal and the width of the female die opening desired. The back also has a rule for calculating the tons of pressure needed for punching three types of metal, given the gauge of the metal and the diameter of the hole.

The front is marked: DREIS & KRUMP (/) MANUFACTURING COMPANY (/) Mfrs. of CHICAGO STEEL PRESS BRAKES. The right side has a logo with the letters D&K in a diamond; the company stopped using this logo by about 1960. On the back, the left side is marked: DREIS & KRUMP (/) MFG. CO., (/) CHICAGO 36. The lower right corner is marked: Copyright 1944, Perry Graf Corp., Maywood, Ill.

Dreis & Krump was one of many businesses that turned to Perrygraf (or Perry Graf) Corporation for promotional slide rules and charts. In 1934, machinery inspector Lester E. Perry (1901–1991) came up with the idea of equipping salespeople with slide charts so that they could immediately answer customers' questions. Perrygraf Corporation, the company he established in the Chicago, Ill., suburbs, quickly became a dominant force in this market.

References: Walter Shawlee II, "The Wonderful World of Slide Charts, Wheel Charts, and Perrygrafs," Sphere Research Corp., http://sphere.bc.ca/test/perrygraf.html; "People: Perrygraf," Waywiser, Harvard University Department of the History of Science website.

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